This invention relates generally to boilers and more particularly to a new and improved modular boiler.
It has already been proposed to recirculate a part of the burned gases in solid, liquid or gaseous fuel boilers by returning them into the burner. On the other hand, it has not been proposed that a recirculation of the gases within the inside of the combustion chamber itself be effected. This recirculation could nevertheless have numerous advantages. It would increase the time of stay of the burned gases in the boiler and therefore would decrease the rate of formation of NO.sub.x. This reinjection could be used also to protect the walls of the combustion chamber, at least in part, from the flame, reducing the rate of formation of NO.sub.x by heat.